Why biologists don’t put too much stock in race

Race is perhaps the worst idea ever to come out of science. Scientists were responsible for officially dividing human beings into Europeans, Africans, Asians and Native Americans and promoting these groups as subspecies or separate species altogether. That happened back in the 18th century, but the division lends the feel of scientific legitimacy to the prejudice that haunts the 21st.

Racial tension proved a major point of contention in the first 2016 presidential debate, and yet just days before, scientists announced they’d used wide-ranging samples of DNA to add new detail to the consensus story that we all share a relatively recent common origin in Africa. While many human species and sub-species once roamed the planet, there’s abundant evidence that beyond a small genetic contribution from Neanderthals and a couple of other subspecies, only one branch of humanity survived to the present day.

Up for grabs was whether modern non-Africans stemmed from one or more migrations out of Africa. The newest data suggests there was a single journey – that sometime between 50,000 and 80,000 years ago, a single population of humans left Africa and went on to settle in Asia, Europe, the Americas, the South Pacific, and everywhere else. But this finding amounts to just dotting the i’s and crossing the t’s on a scientific view that long ago rendered notion of human races obsolete.

“We never use the term ‘race,’” said Harvard geneticist Swapan Mallick, an author on one of the papers revealing the latest DNA-based human story. “We’re all part of the tapestry of humanity, and it’s interesting to see how we got where we are.”

That’s not to deny that people vary in skin color and other visible traits. Whether you’re dark or light, lanky or stocky depends in part on the sunlight intensity and climate in the regions where your ancestors lived. Nor is it to deny that racism exists – but in large part, it reflects a misinterpretation of those superficial characteristics.

“There is a profound misunderstanding of what race really is,” Harvard anthropology professor Daniel Lieberman said at an event the night after the presidential debate. “Race is a scientifically indefensible concept with no biological basis as applied to humans.”

Consider the fact that most of the race boxes people tick off on census forms were invented by creationists, such as Swedish biologist Carolus Linnaeus. In 1758, he declared that humans could be divided into races he described as white (European), red (Native American), black (African) and yellow (Asian).

He also attributed various unflattering personality traits to all the races except for whites. In subsequent decades, scientists of European ancestry argued over whether God created the races separately or whether they diverged from a common creationist origin.

In the 19th century, scientists used race not just to classify people but to justify slavery by painting Africans as inferior, according to Joseph Graves, a geneticist at North Carolina A&T State University who spoke at Harvard this week. One of the world’s most prominent American scientists of the mid-1800s, Samuel Morton, collected skulls from all over the world and attempted to demonstrate that those of European ancestry had the world’s biggest heads and were, so he claimed, intellectually superior.

Scientists subsequently realized that Morton was wrong about whose heads were biggest and the connection between head size and intelligence. There is still controversy about whether Morton cheated or made a statistical error, but his conclusion remains debunked.

Graves – who is the author of several books, including 2005’s “The Race Myth” – said a key turning point occurred when Charles Darwin published “On the Origin of Species” in 1859. From his travels around the world, Darwin realized that there was no scientific reason to divide people into four races. It made just as much sense to him, he wrote later, to divide them into anywhere between two and 63 races.

But not everyone took Darwin’s side. Another influential figure in 19th-century science was Swiss-American biologist Louis Agassiz, whom Graves describes as a “giant” – both in his accomplishments and his sway over his contemporaries. Even after Darwin published his book, Agassiz continued to promote the notion that Africans and Europeans were different species.

Agassiz proposed that the children of mixed couples would be infertile, as are the offspring of horses and donkeys. He was wrong, just like he was wrong in never accepting evolution.

Darwin’s powerful idea didn’t put an end to scientific racism – the eugenics movement of the Progressive Era, for example, tried to cloak racism in evolutionary theory – but in general, 20th-century researchers pushed racism to the scientific fringes. (Historians have shown that Hitler could only fake the scientific credibility of his racist ideology.) And in the 1980s, scientists used DNA to trace all humans back to an origin 200,000 years ago in Africa. This is recent in evolutionary time, given that our lineages split from that of chimpanzees perhaps 7 million years ago.

Refining the story, contemporary scientists have analyzed DNA collected from diverse populations – Aboriginal Australians, Papua New Guineans, Basques, Bedouins and Pygmies. The very nature of the project acknowledges that these groups are distinct enough that their DNA matters in deciphering the human story – but not so distinct that they represent separate races.

Bones and teeth scattered through the Middle East and Asia show people left Africa in many waves, but according to this latest DNA analysis, only one of those waves made a substantial contribution to the current population of humans.

Why are people still so determined to believe that racial categories are distinct, unchanging and rooted in biology?

“It’s not rational,” said Graves. He said one reason Americans are stuck in the 19th century when it comes to race is that many teachers are unprepared to teach human evolution or refuse to out of fear.

Graves sometimes quizzes his students by showing them an image of a man and asking them to guess where he comes from. It appears to show someone most Americans would identify as a black man, and Graves says people assume he’s from Africa or an African American community in the United States. But he’s from the Solomon Islands, which are in the South Pacific.

Faye Flam is a Bloomberg View columnist.

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